Heater



F. A. LOEBEL- Nov. 26, 1963 HEATER 2 Sheets-Sheet 1 Filed Oct. 13, 1960Nov. 26, 1963 F. A. LOEBEL 3,111,935

HEATER 2 Sheets-Sheet 2 Filed 001;. 13, 1960 United States Patent3,111,935 HEATER Frederick A. Loebel, Milwaukee, Wis., assignon toCleaver-Brooks Company, a corporation of Wisconsin Filed Oct. 13, 1960,Ser. No. 62,486 2 Claims. (Cl. 122-33) This invention relates to aheater for viscous fluids, such as asphalt, which tend to decompose whenheated in direct fired heaters.

It is a general object of the invention to provide a new and improvedheater of the type described.

A more specific object is to provide a new and improved heater of thetype described including an outer shell, an inner furnace within theshell, heat exchanger conduit means disposed around the furnace in thespace between the furnace and the shell for conducting fluid to beheated longitudinally and circumferentially through the shell, and meansfor circulating heat transfer liquid in a predetermined path in theshell in heat transfer relationship with the furnace and the conduitmeans.

Another object is to provide a new and improved heater of the typedescribed including a hot gas flue connected with the furnace adjacentone end thereof, encircling the furnace spirally and connected with anexhaust opening.

A further object is to provide a new and improved heater of the typedescribed, including baflie means associated with the heat exchangerconduit means providing a predetermined path for circulation of the heattransfer liquid, and impeller means for circulating the liquid.

It is also an object of the invention to provide a new and improvedheater of the character mentioned including a heat exchanger in the formof a combined conduit means and baflle means in which the conduit meansprovides for circulation of the fluid to be heated longitudinally andcircumferentially through the shell, and the baflle means defines apredetermined path for circulation of heat transfer liquid in heatexchange relationship with the furnace and the conduits.

Other objects and advantages will become readily apparent from thefollowing detailed description taken in connection with the accompanyingdrawings, in which:

FIG. 1 is a side elevational view, partly in section, illustrating aheater embodying the principles of the present invention;

FIG. 2 is a fragmentary sectional view taken at about the line 22 ofFIG. 1; and

FIG. 3 is a fragmentary sectional view taken at about the line 3-3 ofFIG. 1.

While an illustrative embodiment of the invention is shown in thedrawings and will be described in detail herein, the invention issusceptible of embodiment in many different forms, and it should beunderstood that the present disclosure is to be considered as anexemplification of the principles of the invention and is not intendedto limit the invention to the embodiment illustrated. The scope of theinvention will be pointed out in the appended claims.

The purpose of the apparatus of this invention is to heat viscous fluidswhich tend to decompose when heated in direct fired heaters.Decomposition results when the fluid remains in contact, even for shortperiods of time, with extremely hot metal, such as the metal surfaces ofa fire tube or combustion chamber and hot gas flues. The present heateris designed specifically for heating asphalt, though the principles ofthe invention are not limited to this utility. Use is made of oil as anintermediate heat transfer fluid. The heat transfer oil is circulatedover the metal surfaces of the combustion chamber and hot gas fluepreferably at velocities exceeding 3 feet per second in order to controlthe heat exchange. The oil is preferably circulated by means of apropeller type pump, to

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also contact conduit means providing a tortuous path for conducting thefluid to be heated, such as asphalt, through the heater.

Referring to the drawings in greater detail, and particularly FIG. 1,the heater preferably includes an outer shell 20 which may becylindrical and which may be insulated as illustrated at 21. Centrallydisposed within the shell 21 is a cylindrical furnace as at 22 spacedfrom the walls of the outer shell and providing a combustion chamber 23.At the right end as viewed in FIG. 1, the furnace is closed by an endwall 24, and at the left end is provided with refractory material asshown at 25. The refractory material is formed with a centrally disposedopening as at 26 in which there is positioned a burner structure 27. Theburner structure may be properly provided with fuel supply and ignitioncontrol means in any conventional or other suitable manner. A burnertube 30 in which the burner structure is positioned, opens at the leftend into a hollow end cap or closure member 31 to which combustion airis supplied by means of a fan as at 33 suitably driven by a motor as at34. The insulated outer shell may be suitably supported on skids or thelike as illustrated at 38.

The products of combustion pass from the combustion chamber 23 to a hotgas flue 32 connected to the furnace as at 33-, adjacent the right endthereof, spirally encircling the furnace toward the left end and openingto a chamber 35 having an exhaust opening in communication with anexhaust stack as at 36.

Positioned concentrically around the cylindrical furnace 22, in spacedrelation between the furnace and the shell 23, is a heat exchangergenerally designated preferably in the form of a combined conduit meansand baffle means, the conduit means for conducting the fluid to beheated, such as asphalt, in tortuous paths longitudinally andcircinnferentially through the heater, and the baffle means providing adetermined path for circulation of heat exchange liquid through theheater in heat exchange relationship with the furnace 22, the flue 32and the conduit means for the fluid to be heated. The heat exchangerincludes a cylindrical baflle 42 concentric around the furnace 22 andspaced between the furnace and the outer shell 20. Adjacent the rightend as viewed in FIG. 1, the member 42 has secured thereto an annularfrusto-conic closure member as at 43 provided with a central opening as44. The members 42 and 43, secured together suitably as by welding, maybe supported in the outer shell 20 by any suitable means.

A propeller or impeller 45 is positioned in the central opening 44 andsecured on a drive shaft 46 so that when rotated, heat transfer fluid isdrawn into the propeller from the right end of the heater through aguide means 46a and pumped or propelled outwardly toward the left asviewed in FIG. 1. The pump drive shaft 46 may be provided with suitablepulley means as at 47 connected by belt means 48 to pulley means 43 onthe shaft of a drive motor 50*. Provision is thus made for circulationof the heat transfer liquid in a predetermined path determined by thebaflle members 42 and 43, including movement of the heat transfer liquidto the left as viewed in FIG. 1, through the annular space between thefurnace 22 and a cylindrical baflle 42, in heat exchange relationshipwith the furnace 22 and the spiral hot gas flue 32. At the left end ofthe heater, the heat transfer liquid passes radially outwardly aroundthe cylindrical baffle and toward the right end of the heater, in heatexchange relationship with the tubes for conducting asphalt through theheater, and back to the pump 45.

An annular series of horizontally disposed tubes 52 is arrangedconcentrically around the cylindrical bafie 42. Opposite ends of thetubes 52 are connected respectively to headers or manifolds 53 and 54-,in the form of annu- 3 lar tubular elements of rectangular crosssection. An inlet fitting 55 and an outlet fitting 56 communicate withthe header 54.

Baffles or dividers are positioned in the header 54 at angularly spacedpositions as illustrated at 58, 59, 69 and 61. In the header 5'3,battles are positioned as illustrated at 63, 64 and 65. This efiectivelydivides the tubes 52 into six angularly spaced groups, so that fluidfrom the inlet 55 flows back and forth in the tubes in a tortuouspath tothe outlet 56, flowing longitudinally to the left in FIG. 1 throughthree groups of tubes and longitudinally toward the right in FIG. 1through three groups of tubes. It will be understood that the adjacentinlet 55 and outlet 56 are separated by the baflies 58 and 63. The firstgroup of tubes is positioned between the battles 58 and 59, the fluidflowing to the left in FIG. 1 through this group of tubes. The secondgroup of tubes is positioned between the baflie 59 in the header 54 andthe baflie 65 in the header 53, the fluid flowing toward the right inFIG. 1 through this group of tubes. The third group of tubes occursbetween the baffle 65 in the header 53 and the baffle 60 in the header54, the fluid flowing toward the left in FIG. 1 through this group oftubes. Continuing in this fashion, it will be understood that the fluidto be heated makes six passes back and forth longitudinally through theheater and circumferentially around the annular series of tubes to theoutlet 56, while at the same time heat transfer oil is circulatedthrough the shell 20 in heat exchange relationship with the furnace, theflue 32 and the tubes 52.

The header 54 and the annular closure member 43 may be relatively bracedby angularly spaced braces in the form of triangular plates as at 68suitably secured to both the closure member and the header as bywelding, for example.

In order to provide for expansion of the heat exchange liquid in theshell 20 during operation of the burner, the chamber within the shell20* is connected by a conduit 69 to an expansion tank 70 suitablysupported above the insulated shell 20.

I claim:

1. In a compact heater for viscous fluids which tend to decompose whenheated in direct fired heaters, a generally cylindrical outer shell ofrelatively large diameter, a generally cylindrical furnace tube ofrelatively large diameter centrally disposed in the outer shell andspaced therefrom, thereby providing a relatively thin annular spacearound the furnace in the shell for heat transfer liquid, a hot gas fluehaving a diameter about half the thickness of said annular space,connected to the furnace tube adjacent one end thereof and closelyspirally encircling the furnace tube to the other end thereof, a unitarycombined bafile and conduit means encircling the furnace in spacedrelation between the furnace and the outer shell, including acylindrical baflie closely encircling the flue providing a closedcirculation path for the heat transfer liquid extending longitudinallysubstantially the entire length of the shell in one direction inside thebaflie and in the opposite direction outside the bafllc, and including asingle layer of tubular means of relatively small diameter supported onthe baflle and extending substantially the entire length of the shelland arranged around the circumference of the baflle closely adjacentthereto and closely adjacent the outer shell for conducting fluid to beheated longitudinally throughout substantially the entire length of theshell and circumferentially substantially the entire circumference ofthe shell, and means for circulating heat transfer liquid in said closedcirculation path in heat exchange relationship with the furnace, theflue and said tubular means.

2. A combination as defined in claim I, wherein said tubular meanscomprises an annular series of closely adjacent tubes, an annulartubular header on the cylindrical baflle at each end of the tubes eachconnected to the adjacent tube ends, an inlet fitting connected to oneheader, an outlet fitting connected to one header, and dividers in theheaders grouping the tubes and providing a flow path for fluid to beheated from the inlet fitting longitudinally back and forth through thetubes, around the headers and to the outlet fitting.

References Cited in the file of this patent UNITED STATES PATENTS1,980,424 Morgan Nov. 13, 1934 2,055,949 Sharp Sept. 29, 1936 2,582,134Kimmell et a1 Jan. 8, 1952 2,656,821 Ray Oct. 27, 1953 2,924,203 LoebelFeb. 9, 1960 FOREIGN PATENTS 717,542 Great Britain Oct. 27, 1954

1. IN A COMPACT HEATER FOR VISCOUS FLUIDS WHICH TEND TO DECOMPOSE WHENHEATED IN DIRECT FIRED HEATERS, A GENERALLY CYLINDRICAL OUTER SHELL OFRELATIVELY LARGE DIAMETER, A GENERALLY CYLINDRICAL FURNACE TUBE OFRELATIVELY LARGE DIAMETER CENTRALLY DISPOSED IN THE OUTER SHELL ANDSPACED THEREFROM, THEREBY PROVIDING A RELATIVELY THIN ANNULAR SPACEAROUND THE FURNACE IN THE SHELL FOR HEAT TRANSFER LIQUID, A HOT GAS FLUEHAVING A DIAMETER ABOUT HALF THE THICKNESS OF SAID ANNULAR SPACE,CONNECTED TO THE FURNACE TUBE ADJACENT ONE END THEREOF AND CLOSELYSPIRALLY ENCIRCLING THE FURNACE TUBE TO THE OTHER END THEREOF, A UNITARYCOMBINED BAFFLE AND CONDUIT MEANS ENCIRCLING THE FURNACE IN SPACEDRELATION BETWEEN THE FURNACE AND THE OUTER SHELL, INCLUDING ACYLINDRICAL BAFFLE CLOSELY ENCIRCLING THE FLUE PROVIDING A CLOSEDCIRCULATION PATH FOR THE HEAT TRANSFER LIQUID EXTENDING LONGITUDINALLYSUBSTANTIALLY THE ENTIRE LENGTH OF THE SHELL IN ONE DIRECTION INSIDE THEBAFFLE AND IN THE OPPOSITE DIRECTION OUTSIDE THE BAFFLE, AND INCLUDING ASINGLE LAYER OF TUBULAR MEANS OF RELATIVELY SMALL DIAMETER SUPPORTED ONTHE BAFFLE AND EXTENDING SUBSTANTIALLY THE ENTIRE LENGTH OF THE SHELLAND ARRANGED AROUND THE CIRCUMFERENCE OF THE BAFFLE CLOSELY ADJACENTTHERETO AND CLOSELY ADJACENT THE OUTER SHELL FOR CONDUCTING FLUID TO BEHEATED LONGITUDINALLY THROUGHOUT SUBSTANTIALLY THE ENTIRE LENGTH OF THESHELL AND CIRCUMFERENTIALLY SUBSTANTIALLY THE ENTIRE CIRCUMFERENCE OFTHE SHELL, AND MEANS FOR CIRCULATING HEAT TRANSFER LIQUID IN SAID CLOSEDCIRCULATION PATH IN HEAT EXCHANGE RELATIONSHIP WITH THE FURNACE, THEFLUE AND SAID TUBULAR MEANS.